Page 164 - Embedded Microprocessor Systems Real World Design

processors, the vector can be an actual instruction that is executed just as if it
occurred in ordinary code. Other processors expect a number that is translated by
the processor into an address.
Figure 5.2 shows the three methods of generating a vector to the processor: from
an external interrupt controller, from an internal interrupt controller, or from the
peripheral itself. On some processors that use an internal controller, the internal
hardware may not produce a separate interrupt cycle with a true vector, but the
effect is the same.

FROM { EXTERNAL

INTERRUPT
REQUESTS
CONTROLLER
PERIPHERALS INTERRUPT INTERRUPT * PROCESSOR
VECTOR

i INTERRUPT

INTERRUPT - INTERNAL
REQUESTS
PERIPHERALS CONTROLLER INTERRUPT PROCESSOR
VECTOR

PERIPHERALS
REQUESTING
INTERRUPTS

PROCESSOR
--/ VECTORS
I

Figure 5.2
Interrupt Vector Generation.

Interrupts in Embedded Systems 145